Field of the Invention
There is a need to remotely monitor latch bolts and dead bolts, particularly when electric strikes are used. The need also arises from time to time when manual locking devices are used. The present invention has to do with the development of a magnetic reed switch assembly which substantially improves the reliability of remote monitoring and which substantially eliminates the need for maintenance as compared with prior mechanical switches.
The Related Art
Prior to applicants' development of the present invention, mechanical switches were used to monitor the positions of latch bolts or dead bolts, i.e., monitoring whether or not the door was open and, if the latch was engaged, whether or not the dead bolt, if any, was in a locked or unlocked position and to monitor whether the keeper of the electric strike was locked or unlocked. But mechanical switches have a relatively short useful life as compared with the useful life of a latch or dead bolt. Most mechanical switches are comprised of micro switch assemblies which have an electrical life of about 50,000 cycles and a mechanical life of about 100,000 cycles. Electric strikes, on the other hand, may have a useful life of 250,000 cycles or more. Micro switch failure, therefore, requires maintenance several times over the life of the strike. Of course, the mechanical switch requires mechanical actuation which can lead to mechanical failures in addition to electrical failures. Mechanical switches are detrimentally affected by moisture and they can be detrimentally affected by oil. It is also difficult and expensive to protect a mechanical switch from moisture in an outdoor application. The result is that mechanical switches generally are not used in outdoor applications or other applications that may expose them to water.
Magnetic reed switches have not previously been used in lock monitoring because they are delicate and relatively expensive as compared with mechanical switches. But magnetic reed switches have a rated life of 10+ million cycles, far longer than presently available locking mechanisms. Applicants have now invented a design which protects the reed switch within the lock mechanism. And, as to expense, the cost of the reed switch is more than offset by the reduced maintenance costs associated with mechanical switches.